Does he have reasons to be mad?

I have had a boyfriend for 2 years, we were on a break and i developed feelings for someone else i told me boyfriend about these feelings and he treating me as if i cheated on him is that understandable? im not sure if he is puting me in me through a guilt trip? i do not have the feelings for this person now so how do i make it up to my boyfriend and make him feel like he can trust me again? how do i make him feel that i dont like this other person?